Curved keyboard keypad and contact structure

ABSTRACT

A keypad is disclosed having a rigid plate with openings. A flexible sheet of the keypad has keys which protrude through the openings of the rigid plate. The keypad further includes a rigid insertion plate and a flexible contact sheet with dome-shaped contacts configured to contact the keys. The rigid plate and the rigid insertion plate have a curved shape, where the flexible sheet and the flexible contact sheet are located between the rigid plate and the rigid insertion plate to conform to the curved shape. The curved shape is concave along a longitudinal axis of the keypad and convex along the keypad transversal axis. Further, the top surfaces of the keys protruding from the openings are contoured to conform to the curved shape.

BACKGROUND OF THE INVENTION

The invention relates to a curved keypad device, comprising:

on the outside, keys to be handled by the user, and

a contact configuration for containing contacts for each of the keys.

Such a device finds highly significant applications in lots of fields:remote control devices, pocket calculators, telephone terminals, etc.

A device of this type is described in Patent Specification PCT No. WO94/04974. This document describes a keypad for a computer which is tohave a great quality of touch. It has a large number of separate keyspositioned to correspond to a profile dictated by ergonomics. The factthat a large number of separate keys are to be provided complicates themanufacture and this does not permit to obtain an inexpensive product.

SUMMARY OF THE INVENTION

The invention proposes a device of the type mentioned above which may beprovided in an economic manner while having a good quality of touch.

Therefore, such a device is characterized in that said keypad comprises:

a first flexible key-carrying sheet,

a second flexible contact sheet for forming said contact configuration,and in that said sheets are curved for conforming in shape to saidprofile.

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a device according to the invention;

FIG. 2 shows an exploded view of the keypad before its mounting,

FIG. 3 shows an exploded view of the keypad after its mounting,

FIG. 4 shows the section of a surface to which the tops of the keys areto be aligned, and

FIG. 5 shows how the pressure of the finger influences the keys.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The device shown in FIG. 1 is a telecommunications terminal of thehandheld type which is connected to its base by radio. This device has arounded form to give a handy grip. The device shown in this FIG. 1 hasan earpiece 1, a microphone 2, a screen 3, an antenna 4 and a keypad 5which conforms to the profile defined by the form of the device. Thisprofile may be split up into two profile lines. Along the longitudinalaxis L, the keypad 5 has a concave profile line and along thetransversal axis T a convex profile line. The keypad 5 comprises keys6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6i which protrude outward and presentthemselves harmoniously, similar to said profile.

FIG. 2 shows a part of the keypad 5 which relates to the second profileline. The keypad 5 is formed by the following component parts:

A rigid exterior plate 10 takes the form of the device and has a certainprofile so that the assembly has a harmonious form. This plate 10 hasopenings 11a-11i to let all the keys 6a-6i pass through.

The keys 6a-6i are formed on a key-carrying sheet 15. Only three keys6c, 6f and 6i are shown in FIG. 2.

A contact sheet 20 comprising the contacts 21c, 21f and 21i in the formof a dome are only visible in FIG. 2. These contacts are each associatedto the respective keys 6c, 6f and 6i.

A rigid supporting or insertion plate 25 for protecting the circuits isaccommodated inside the device and has the same profile as the plate 10.

These two sheets are made of flexible plastic material of the elastomertype for the first sheet, of the Mylar type for the second sheet,surrounding metallic lamellas.

Once manufactured, the sheets 15 and 20 always occur in planar form, andtherefore they are shown as such in this Figure.

FIG. 3 shows the keypad 5 once it has been mounted, that is to say, oncethe plate 10 which can be clipped into the body of the device, comesclose to the intermediate plate 25 taking the shape of the body of thedevice. This action provides that the sheets 15 and 20 are curved andconform in shape to the desired profile.

For providing that the tops of the keys homogeneously pass through plate10, these keys are to fit in a section S of a reduced-size surface ofthe profile during manufacture to compensate for the excessiveunevennesses caused by the profile, as is shown in FIG. 4. This Figurealso shows the mechanical cooperation of the two sheets 15 and 20. Thepresence will be noted of studs 30c, 30f and 30i assigned each to keys6c, 6f and 6i intended to depend on the domes 21c, 21f and 21i.

This curving of the sheets 15 and 20 is particularly advantageous forobtaining free contacts, as is shown in FIG. 5. Indeed, the pressure Fof the user's finger is exerted in a normal direction D to the surfaceof the device, so that the pin 30c receiving the force F in thedirection D normally transmits the force F to the dome 21c, thus in bestconditions.

It will be noted that the keypad, being pressed against the casing ofthe device, takes up minimum space in the device.

It is to be preferred for certain marketed contact sheets 20 that theyare curved only along a profile axis.

We claim:
 1. A keypad comprising:a rigid plate having openings; aflexible sheet having keys which protrude through said openings; aflexible contact sheet having contacts configured to contact said keys;and a rigid insertion plate, said rigid plate and said rigid insertionplate having a curved shape, wherein said flexible sheet and saidflexible contact sheet are located between said rigid plate and saidrigid insertion plate to conform to said curved shape.
 2. The keypad ofclaim 1, wherein top surfaces of said keys protruding from said openingsare contoured to conform to said curved shape.
 3. The keypad of claim 1,wherein said curved shape is concave along a longitudinal axis of saidkeypad.
 4. The keypad of claim 1, wherein said curved shape is convexalong a transversal axis of said keypad.
 5. The keypad of claim 1,wherein said curved shape is concave along a longitudinal axis of saidkeypad and convex along a transversal axis of said keypad.
 6. The keypadof claim 1, wherein said contacts are dome-shaped.
 7. A keypadcomprising:a rigid plate having openings; a flexible sheet having keyswhich protrude through said openings; a flexible contact sheet havingcontacts configured to contact said keys; and a rigid insertion plate,said flexible sheet and said flexible contact sheet are located betweensaid rigid plate and said rigid insertion plate, wherein said rigidplate and said rigid insertion plate are concave along a longitudinalaxis of said keypad and convex along a transversal axis of said keypad.8. The keypad of claim 7, wherein top surfaces of said keys protrudingfrom said openings are contoured to conform to said curved shape.
 9. Thekeypad of claim 7, wherein said contacts are dome-shaped.
 10. A keypadcomprising:a rigid insertion plate; a rigid plate having openings, saidrigid plate and said rigid insertion plate having a curved shape; aflexible sheet located between said rigid plate and said rigid insertionplate to conform to said curved shape, wherein top surfaces of said keysprotruding from said openings conform to said curved shape; and aflexible contact sheet located between said rigid insertion plate andsaid flexible sheet, said flexible contact sheet having contacts forengaging said keys.
 11. The keypad of claim 10, wherein said curvedshape is concave along a longitudinal axis of said keypad.
 12. Thekeypad of claim 10, wherein said curved shape is convex along atransversal axis of said keypad.
 13. The keypad of claim 10, whereinsaid curved shape is concave along a longitudinal axis of said keypadand convex along a transversal axis of said keypad.
 14. The keypad ofclaim 10, wherein said contacts are dome-shaped.
 15. A device having akeypad, said keypad comprising:a rigid plate having openings; a flexiblesheet having keys which protrude through said openings; a flexiblecontact sheet having contacts configured to contact said keys; and arigid insertion plate, said rigid plate and said rigid insertion platehaving a curved shape, wherein said flexible sheet and said flexiblecontact sheet are located between said rigid plate and said rigidinsertion plate to conform to said curved shape.
 16. The device of claim15, wherein top surfaces of said keys protruding from said openings arecontoured to conform to said curved shape.
 17. The device of claim 15,wherein said curved shape is concave along a longitudinal axis of saidkeypad.
 18. The device of claim 15, wherein said curved shape is convexalong a transversal axis of said keypad.
 19. The device of claim 15,wherein said curved shape is concave along a longitudinal axis of saidkeypad and convex along a transversal axis of said keypad.